A very tough one to price, but it's about time someone had a shot at it.

http://www.tf2outpost.com/trade/9295207 Offers:

10 pure straight away

My ballcap (yet again) + 1 bill - 11 in unusuals

Harvest moon Conquistador (9-10) + Stormy storm Dragonborn Helmet (3) - Totalling 12 in unusuals

http://www.tf2outpost.com/user/72384/2 - Sold for 8 pure (I think, this was around halloween so the prices would not have had time to jump yet).

Apologies for the lack of evidence, I'll try and look around for more.